This invention relates to information display signs or devices of the general type illustrated in U.S. Pat. No. 3,562,938 to Salam, granted Feb. 16, 1971. Such devices basically comprise a panel having a plurality of discrete light-transmitting areas arranged along transversely spaced upright columns and surrounded by a background which is preferably, but not essentially, opaque. The panel is normally back-lighted and the desired display is usually viewed as light transmitted through the discrete areas. Circular discs are mounted behind the panel for planar movement of each disc between a first position overlying a light-transmitting area and a second position clear of such area. By arranging the individual discs in one or the other of such positions, any desired pattern of light transmission can be achieved through the individual light-transmitting areas, thereby producing the desired visual pattern on the viewed panel.
Other patents relating to this general type of display are U.S. Pat. Nos. 3,685,040, 3,601,914 and 3,659,366. They are illustrative of prior attempts to fabricate this general type of display by laminating successive sheets of materials to one another.
According to this disclosure, the circular discs are mounted within recesses formed in the panel. The method of producing the panel comprises the step of pressing one surface of a sheet of permanently compressible material by use of a mold having an exterior configuration that is complementary to the desired configuration and pattern of the recesses. The remaining surface of the sheet is maintained in a planar condition. The pressing step reduces the sheet thickness in a pattern that corresponds to the desired pattern of the recesses about the sheet. Normally these recesses are formed along upright columns and transverse lines. Apertures are also formed through the sheet at locations each bounded by an identical corresponding portion of each recess. The recess typically assumes a cardioid shape, with the aperture at one side thereof. By overlaying the sheet of foam with suitable cover layers of lighttransmitting material, one can produce an effective rigid panel having only two or three laminations and suitable for use in the general type of display sign described above.